In medicine, biopsying a sample of tissue remains the gold standard for pursuing a diagnosis of tissue pathology. The biopsied tissue is then examined histologically for evidence of dysplasia and cancerous transformation to yield the diagnosis.
The treatment of choice, particularly in the women of childbearing age, for cervical dysplasia involving the cervical canal or for more than one degree of discrepancy between the degree of dysplasia represented on the Pap smear versus colposcopic directed biopsy is conization of the cervix. In a conization of the cervical tissue, the traditional cold knife procedure involved removing a cone shaped tissue specimen from the cervix with the axis of the cone centered on the axis of the endocervical canal. The cone base is positioned at the external cervical os, oriented with the cone apex toward the internal cervical os. With the advent of electrocautery devices the specimen shape may be refined to a more anatomically directed biopsy specimen that maintains a more accurate depth of surgical resection but seldom resembles an actual cone. There are a number of methods and devices for performing this procedure.
The ideal endocervical biopsy yields a cylinder of tissue approximately two centimeters in length and five to seven mm deep on all faces centered on the axis of the endocervical canal. Seldom is the ideal achieved, but there are several methods available. First, surgically excise the tissue. Surgical excision, i.e., cold knife conization, is accomplished with a conventional scalpel.
Second, use a loop electrosurgical excision procedure (LEEP) to first create a superficial excision followed by a second deeper excision extending further along the endocervical canal toward the internal cervical os. The loop excision uses a loop of wire for electrocautery excision of the specimen. The loop is handheld with the first pass depth less than two centimeters, consequently, the need for more than one pass in order to approach the ideal endocervical treatment depth.
Third, use a modified LEEP electrode that is shaped to combine the superficial and deep excisions into one pass. The modified LEEP conization electrodes consist of an insulated stiff rod with a wire electrode extending from the tip of the rod to a cross arm, which approximates the configuration of a cone specimen.
A fourth method uses CO.sub.2 laser energy in lieu of a scalpel for performing an excisional cervical conization.
Sharp excision techniques using devices such as a scalpel, have the advantage for controlled tissue removal and minimal tissue injury with preservation of resection margins for clarity of histologic analysis, but the procedure has poor anatomic control. A drawback to cold knife conization excision over LEEP is the increased blood loss from the wound edge. Because of their size, including the handle, scalpels are more difficult to wield in the closer confines of the vaginal vault. A number of devices for mounting, holding, and modifying scalpel blades have been developed, but these devices have proven to be either difficult to keep the excision centered or difficult to turn while in the vaginal vault.
LEEP has improved blood loss control, but the straight stiff rods are difficult to use within the confines of the vaginal vault because of the angle differences between the long axis of the vaginal vault to the long axis of the endocervical canal. The difficulty in obtaining proper alignment of the device to the axis of the endocervical canal leads to off centered and or tilted excisions that run a significant risk of only partially excising abnormal tissue, completely missing the abnormal tissue, and or removing excessive amounts of normal tissue.
What is needed is a device that is capable of concentrically removing cervical tissue around the endocervical axis of rotation at an appropriate biopsy depth with minimal blood loss and minimal injury to cervical margin tissues.